atlantoaxial rotatory fixation – This refers to a rotational dislocation of the normal alignment of the first vertebra of the spine (C! or Atlas) from the second vertebra (C2 or Axis) with the dislocation being of such a severity that it will not spontaneously relocate back into a normal alignment.  In such cases when the head is maximally rotated to the opposite side the rotational malalignment of C1 on C2 is unchanged or “fixed”.